It seems that the problem is that you are centering the window, and some time after that new content is loading.
In other words: The center is called before the window gets a new size through the loaded content.
To prevent this, you must bind windows to the event and center it.
Something along the lines ( Beware: register this event only once ):
var win = $("#myWindow").data("kendoWindow"); win.bind("refresh", function() { win.center(); win.open(); });
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